1. Field of the Invention
The present invention relates to a shorted monopole antenna, and more particularly, to a small-size shorted monopole antenna which is able to cover multiband operations in mobile communication devices.
2. Description of the Related Art
The fast development of wireless communication technology has created various applications and products, such as portable communication devices, which are the hottest communication products at present. In order to be light, thin, and compact and to provide multi-band operation capabilities, portable communication devices must be equipped with small antennas; therefore, various antenna miniaturization techniques have been proposed to meet requirements for portable communication devices.
Presently, a shorted monopole antenna of a portable communication device uses a multiple-resonance path or a dual-resonance path approach to achieve multi-band operations, for example, in the prior art cases such as the Taiwan patent no. I254,493, entitled “Dual-Band Inverted-F Antenna”, and the Taiwan patent no. I276,248, entitled “An Internal Multiband Antenna”, which disclose shorted monopole antennas using dual resonance paths to provide dual-band or multi-band operations. However, using such a dual-resonance or multiple-resonance path approach could have limitations in further minimizing the antenna, making it difficult to meet present requirements of miniaturization of multi-band antennas.
Therefore, it is necessary to provide a shorted monopole antenna to overcome the deficiency encountered by the prior art techniques.